1. Field of Invention
The present invention relates to reactors for semiconductor processing. More particularly, the present invention provides an apparatus for generating a substantially symmetrical reactor for semiconductor processing.
2. Description of Related Art
Semiconductor manufacturing includes the cyclic repetition of several major process steps. Many fabrication processes involve chemical reactions that take place in reactors. The driving force for these chemical reaction processes is to optimize the required chemical reactions by introducing the correct chemicals in the proper vacuum environment while providing energy to drive the reaction. During these chemical action processes, detrimental aspects of the reaction are minimized, such as exposure to moisture, the ambient environment, and contaminants. This optimum condition is reached by carefully introducing the necessary mix of precursor chemicals into the reactor, and then monitoring the chemical reaction to achieve the desired conditions on the wafer surface.
Often chemical reactions for wafer processing occur within the reactor. The reactor is a controlled vacuum environment where chemical reactions occur under controlled conditions. Typically, the following functions are performed within the reactor: controlling gas flow within the reactor and near the wafer; maintaining a prescribed pressure inside the reactor; removing undesirable by-products from the reactor; creating an environment for chemical reactions such as plasma to occur, and controlling the heating and cooling of the water.
Referring to FIG. 1 there is shown an isometric view of a prior art reactor 10 used for semiconductor manufacturing. Typically, the reactor 10 comprises a liner 12, a process chamber 14 and a valve chamber 16. Typically, the liner 12 and the valve chamber 16 are coupled to the process chamber 14. The liner 12, process chamber 14 and valve chamber 16 are adapted to receive a wafer (not shown) through a slotted opening 18 that includes a liner aperture, a process chamber aperture and a valve chamber aperture. The wafer is transported in and out of the reactor via opening 18 with a transport module (not shown). The wafer sits on the liner 12. The wafer surface is then exposed to the various gases or liquids that are applied in the process chamber 14.
Referring to FIG. 2A, there is shown a cross-sectional view of the prior art reactor 10. The valve chamber 16 and the process chamber 14 are shown as separate components. Alternatively, the valve chamber 16 and the process chamber 14 may be joined together. As shown in FIG. 2A, the liner 12 sits on the process chamber 14.
Referring to FIG. 2B as well as FIG. 1, there is shown an exploded view of the opening 18 and the interface between the liner 12, the process chamber 14 and the valve chamber 16. The opening 18 includes a liner aperture 20 which is a slot defined by the liner 12 adapted to provide passage to a wafer (not shown). The liner aperture 20 is curved and follows the cylindrically shaped portion of the liner 12. The opening 18 also includes a process chamber aperture 22 which is a slot defined by the process chamber 14. The process chamber 14 has a planer face that is adapted to interface with the valve chamber 16. Further still, the opening 18 includes a valve chamber aperture 23 which is a slot defined by the valve chamber 16. The valve chamber aperture 23 is a planar slot configured to receive a slot valve plate 24 to cover the valve chamber aperture 23 so that an adequate vacuum seal can be achieved in the process chamber 14. The slot valve plate 24 is moved by an actuator 25 in a substantially vertical and horizontal direction, thereby provided two degrees of freedom to the movements of the slot valve plate. There is also a liner/chamber gap 26a and 26b which is defined by the gap between the liner 12 and the chamber 14.
In operation, the actuator 25 moves the slot valve plate 24 from a “closed” position to an “open” position and vice versa in a well-known predetermined manner. In the “closed” position, i.e. vacuum enabled position, the slot valve plate 24 covers the valve chamber aperture 23 and the process chamber aperture 22. In the “open” position, i.e. wafer passage position, the actuator 25 moves the slot valve plate 24 to provide passage to the wafer through the liner aperture 20, the process chamber aperture 22 and valve chamber aperture 23. Typically, the first movement of the slot valve plate 24 from the “closed” position to the “open” position requires the slot valve plate 24 to move in an essentially horizontally direction that is away from the valve chamber aperture. Typically, the second movement from the “closed” position to he “open” position requires the slot valve plate 24 to move in an essentially vertical direction that provides passage of the wafer into the reactor 10. Typically, the movement of the slot valve plate 24 from the “open” position to the “closed” position first requires the slot valve plate 24 to move vertically to cover the opening 18, and then secondly the slot valve 24 moves horizontally to sit on the valve chamber 16 and provide a vacuum seal for the valve chamber aperture 23.
In the “closed” position, the liner aperture 20 generates a non-uniform reactor that lacks symmetry. This lack of symmetry affects wafer processing. The resulting effects caused by this lack of symmetry include non-uniform gas distribution, non-uniform gas density, and non-uniform plasma density. Additionally, these effects are magnified by the industry wide trend to increase wafer size while decreasing feature sizes.
Therefore, there is a need to provide a symmetrical reactor that avoids the limitations associated with the non-uniform reactor described above. There are a variety of solutions that provide for the generation of a symmetrical reactor. However, these solutions require adding more actuators, adding bellows, or making substantial modifications to the existing reactor design.
Therefore, there is a need to provide a symmetrical reactor without requiring significant modifications to the well-known reactor design.
Additionally, there is a need for a symmetrical reactor that does not employ additional control circuitry or software.